1. Field of the Invention
The present invention relates to a position measuring system and/or a navigation system, and more particularly to a system using a GPS. The present invention also relates to a navigation method, an information service method, an automotive vehicle, and audio information transmitting and receiving method.
2. Description of the Related Art
Conventionally, a navigation system utilizing a position measuring system using artificial satellites called a GPS (Global Positioning System) has been widely known and has already been in widespread use in vehicles. In addition, a so-called hybrid type navigation system for navigation based on information from a gyro sensor or the like has also been used extensively in tunnels, valleys between tall buildings in town, and so on, where GPS radio wave from a satellite do not reach. A variety of receivers have been developed for position measuring systems using the GPS for applications other than in vehicles.
However, while a conventional system demonstrates its performance to some extent when it can receive a GPS radio wave, it has a disadvantage in that data from a gyro sensor, generated at a place where a GPS radio wave does not reach, include so many cumulative errors that they are not worth using. Also, while map matching is frequently performed, this is a mere correction of data so that an absolute measuring accuracy cannot be improved thereby. If the matching leads to an erroneous road, a worse result is introduced than without matching.
In addition, even when a GPS radio wave can be received, it cannot straightforwardly be said that a sufficient accuracy can be always provided since there is a mode for intentionally degrading the accuracy by the administrator of the GPS (the Department of Defence of the United States), and since radio wave transmission conditions may be disturbed by a perturbed ionospheric layer or the like which deteriorates the measuring accuracy.